Testing Heating System

[whazza22]

When testing the insulation resistance on a s-plan heating system, do you need to disconnect all components or do you just disconnect the feed to programmer and test only between the d.b and feed?

Thanks

 

[Andyfm]

Are you trying to find a fault or testing for readings so a certificate can be issued

 

[whazza22]

Just part of a full test. Worried that parts may be damaged with 500v.

 

[Deleted member 9648]

As long as you dont do a L-N IR test you wont do any damage....however if the boiler is a modern job with PCB's etc I would isolate that to be on the safe side.

 

[lamb]

This is my procedure for a full test on S or Y plan:

1. Isolate at FCU or lock off MCB.

2. Disconnect the load CPC from FCU. Using a long lead, measure R2 from this CPC to each point of the system (metal case of boiler, metal pump, metal motorised valve, and prog. and cyl. stat if these are metal)

3. At the wiring centre, disconnect the fixed wiring which is usually three of 3c+E, one to room stat and two to boiler/prog position. Megger these at 250V each core to earth, then put them back.

4. Visually inspect all flexes along their length.

5. Measure Zs at FCU, ensure it contains 3A fuse (5A if oil boiler). Re-energize the system and carry out a full functional test (boiler fires, motorised valve moves accross, pump spins).

6. Check bonding to gas (oil) and water incoming services. Ensure cross bonding is in place below boiler, if required by manufacturers instructions for gas appliance.

7. Finally, I always check that the radiator nearest the roomstat is fitted with a pair of lockshield valves. This is for compliance with building regs, not BS7671.

8. Note limitations on cert, record R2 and Zs, sign cert.